Read Object as a Stream

  namespace 
  
 gcs 
  
 = 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 storage 
 ; 
 []( 
 gcs 
 :: 
 Client 
  
 client 
 , 
  
 std 
 :: 
 string 
  
 const 
&  
 bucket_name 
 , 
  
 std 
 :: 
 string 
  
 const 
&  
 object_name 
 ) 
  
 { 
  
 gcs 
 :: 
 ObjectReadStream 
  
 stream 
  
 = 
  
 client 
 . 
 ReadObject 
 ( 
 bucket_name 
 , 
  
 object_name 
 ); 
  
 int 
  
 count 
  
 = 
  
 0 
 ; 
  
 std 
 :: 
 string 
  
 line 
 ; 
  
 while 
  
 ( 
 std 
 :: 
 getline 
 ( 
 stream 
 , 
  
 line 
 , 
  
 '\n' 
 )) 
  
 { 
  
 ++ 
 count 
 ; 
  
 } 
  
 if 
  
 ( 
 stream 
 . 
 bad 
 ()) 
  
 throw 
  
 google 
 :: 
 cloud 
 :: 
 Status 
 ( 
 stream 
 . 
 status 
 ()); 
  
 std 
 :: 
 cout 
 << 
 "The object has " 
 << 
 count 
 << 
 " lines 
 \n 
 " 
 ; 
 } 
 

  using 
  
  Google.Cloud.Storage.V1 
 
 ; 
 using 
  
 System 
 ; 
 using 
  
 System.IO 
 ; 
 public 
  
 class 
  
 DownloadFileSample 
 { 
  
 public 
  
 void 
  
 DownloadFile 
 ( 
  
 string 
  
 bucketName 
  
 = 
  
 "your-unique-bucket-name" 
 , 
  
 string 
  
 objectName 
  
 = 
  
 "my-file-name" 
 , 
  
 string 
  
 localPath 
  
 = 
  
 "my-local-path/my-file-name" 
 ) 
  
 { 
  
 var 
  
 storage 
  
 = 
  
  StorageClient 
 
 . 
  Create 
 
 (); 
  
 using 
  
 var 
  
 outputFile 
  
 = 
  
 File 
 . 
 OpenWrite 
 ( 
 localPath 
 ); 
  
 storage 
 . 
 DownloadObject 
 ( 
 bucketName 
 , 
  
 objectName 
 , 
  
 outputFile 
 ); 
  
 Console 
 . 
 WriteLine 
 ( 
 $"Downloaded {objectName} to {localPath}." 
 ); 
  
 } 
 } 
 

  import 
  
 ( 
  
 "context" 
  
 "fmt" 
  
 "io" 
  
 "time" 
  
 "cloud.google.com/go/storage" 
 ) 
 // downloadFileIntoMemory downloads an object. 
 func 
  
 downloadFileIntoMemory 
 ( 
 w 
  
 io 
 . 
  Writer 
 
 , 
  
 bucket 
 , 
  
 object 
  
 string 
 ) 
  
 ([] 
 byte 
 , 
  
 error 
 ) 
  
 { 
  
 // bucket := "bucket-name" 
  
 // object := "object-name" 
  
 ctx 
  
 := 
  
 context 
 . 
 Background 
 () 
  
 client 
 , 
  
 err 
  
 := 
  
 storage 
 . 
 NewClient 
 ( 
 ctx 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 nil 
 , 
  
 fmt 
 . 
 Errorf 
 ( 
 "storage.NewClient: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 defer 
  
 client 
 . 
 Close 
 () 
  
 ctx 
 , 
  
 cancel 
  
 := 
  
 context 
 . 
 WithTimeout 
 ( 
 ctx 
 , 
  
 time 
 . 
 Second 
 * 
 50 
 ) 
  
 defer 
  
 cancel 
 () 
  
 rc 
 , 
  
 err 
  
 := 
  
 client 
 . 
  Bucket 
 
 ( 
 bucket 
 ). 
  Object 
 
 ( 
 object 
 ). 
  NewReader 
 
 ( 
 ctx 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 nil 
 , 
  
 fmt 
 . 
 Errorf 
 ( 
 "Object(%q).NewReader: %w" 
 , 
  
 object 
 , 
  
 err 
 ) 
  
 } 
  
 defer 
  
 rc 
 . 
 Close 
 () 
  
 data 
 , 
  
 err 
  
 := 
  
 io 
 . 
 ReadAll 
 ( 
 rc 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 nil 
 , 
  
 fmt 
 . 
 Errorf 
 ( 
 "io.ReadAll: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "Blob %v downloaded.\n" 
 , 
  
 object 
 ) 
  
 return 
  
 data 
 , 
  
 nil 
 } 
 

  import 
  
 com.google.cloud. ReadChannel 
 
 ; 
 import 
  
 com.google.cloud.storage. BlobId 
 
 ; 
 import 
  
 com.google.cloud.storage. Storage 
 
 ; 
 import 
  
 com.google.cloud.storage. StorageOptions 
 
 ; 
 import 
  
 com.google.common.io.ByteStreams 
 ; 
 import 
  
 java.io.IOException 
 ; 
 import 
  
 java.nio.channels.FileChannel 
 ; 
 import 
  
 java.nio.file. Path 
 
 ; 
 import 
  
 java.nio.file.Paths 
 ; 
 import 
  
 java.nio.file.StandardOpenOption 
 ; 
 public 
  
 class 
 StreamObjectDownload 
  
 { 
  
 public 
  
 static 
  
 void 
  
 streamObjectDownload 
 ( 
  
  String 
 
  
 projectId 
 , 
  
  String 
 
  
 bucketName 
 , 
  
  String 
 
  
 objectName 
 , 
  
  String 
 
  
 targetFile 
 ) 
  
 throws 
  
 IOException 
  
 { 
  
 // The ID of your GCP project 
  
 // String projectId = "your-project-id"; 
  
 // The ID of your GCS bucket 
  
 // String bucketName = "your-unique-bucket-name"; 
  
 // The ID of your GCS object 
  
 // String objectName = "your-object-name"; 
  
 // The path to the file to download the object to 
  
 // String targetFile = "path/to/your/file"; 
  
  Path 
 
  
 targetFilePath 
  
 = 
  
 Paths 
 . 
 get 
 ( 
 targetFile 
 ); 
  
  Storage 
 
  
 storage 
  
 = 
  
  StorageOptions 
 
 . 
 newBuilder 
 (). 
 setProjectId 
 ( 
 projectId 
 ). 
 build 
 (). 
 getService 
 (); 
  
 try 
  
 ( 
  ReadChannel 
 
  
 reader 
  
 = 
  
 storage 
 . 
  reader 
 
 ( 
 BlobId 
 . 
 of 
 ( 
 bucketName 
 , 
  
 objectName 
 )); 
  
 FileChannel 
  
 targetFileChannel 
  
 = 
  
 FileChannel 
 . 
 open 
 ( 
 targetFilePath 
 , 
  
 StandardOpenOption 
 . 
 WRITE 
 )) 
  
 { 
  
 ByteStreams 
 . 
 copy 
 ( 
 reader 
 , 
  
 targetFileChannel 
 ); 
  
 System 
 . 
 out 
 . 
 println 
 ( 
  
 "Downloaded object " 
  
 + 
  
 objectName 
  
 + 
  
 " from bucket " 
  
 + 
  
 bucketName 
  
 + 
  
 " to " 
  
 + 
  
 targetFile 
  
 + 
  
 " using a ReadChannel." 
 ); 
  
 } 
  
 } 
 } 
 

  /** 
 * TODO(developer): Uncomment the following lines before running the sample. 
 */ 
 // The ID of your GCS bucket 
 // const bucketName = 'your-unique-bucket-name'; 
 // The ID of your GCS file 
 // const fileName = 'your-file-name'; 
 // The filename and file path where you want to download the file 
 // const destFileName = '/local/path/to/file.txt'; 
 // Imports the Google Cloud client library 
 const 
  
 { 
 Storage 
 } 
  
 = 
  
 require 
 ( 
 ' @google-cloud/storage 
' 
 ); 
 // Creates a client 
 const 
  
 storage 
  
 = 
  
 new 
  
 Storage 
 (); 
 async 
  
 function 
  
 streamFileDownload 
 () 
  
 { 
  
 // The example below demonstrates how we can reference a remote file, then 
  
 // pipe its contents to a local file. 
  
 // Once the stream is created, the data can be piped anywhere (process, sdout, etc) 
  
 await 
  
 storage 
  
 . 
 bucket 
 ( 
 bucketName 
 ) 
  
 . 
 file 
 ( 
 fileName 
 ) 
  
 . 
  createReadStream 
 
 () 
  
 //stream is created 
  
 . 
 pipe 
 ( 
 fs 
 . 
  createWriteStream 
 
 ( 
 destFileName 
 )) 
  
 . 
 on 
 ( 
 'finish' 
 , 
  
 () 
  
 = 
>  
 { 
  
 // The file download is complete 
  
 }); 
  
 console 
 . 
 log 
 ( 
  
 `gs:// 
 ${ 
 bucketName 
 } 
 / 
 ${ 
 fileName 
 } 
 downloaded to 
 ${ 
 destFileName 
 } 
 .` 
  
 ); 
 } 
 streamFileDownload 
 (). 
 catch 
 ( 
 console 
 . 
 error 
 ); 
 

  use Google\Cloud\Storage\StorageClient; 
 /** 
 * Download an object from Cloud Storage and save it as a local file. 
 * 
 * @param string $bucketName The name of your Cloud Storage bucket. 
 *        (e.g. 'my-bucket') 
 * @param string $objectName The name of your Cloud Storage object. 
 *        (e.g. 'my-object') 
 * @param string $destination The local destination to save the object. 
 *        (e.g. '/path/to/your/file') 
 */ 
 function download_object(string $bucketName, string $objectName, string $destination): void 
 { 
 $storage = new StorageClient(); 
 $bucket = $storage->bucket($bucketName); 
 $object = $bucket->object($objectName); 
 $object->downloadToFile($destination); 
 printf( 
 'Downloaded gs://%s/%s to %s' . PHP_EOL, 
 $bucketName, 
 $objectName, 
 basename($destination) 
 ); 
 } 
 

  from 
  
 google.cloud 
  
 import 
  storage 
 
 def 
  
 download_blob_to_stream 
 ( 
 bucket_name 
 , 
 source_blob_name 
 , 
 file_obj 
 ): 
  
 """Downloads a blob to a stream or other file-like object.""" 
 # The ID of your GCS bucket 
 # bucket_name = "your-bucket-name" 
 # The ID of your GCS object (blob) 
 # source_blob_name = "storage-object-name" 
 # The stream or file (file-like object) to which the blob will be written 
 # import io 
 # file_obj = io.BytesIO() 
 storage_client 
 = 
  storage 
 
 . 
  Client 
 
 () 
 bucket 
 = 
 storage_client 
 . 
  bucket 
 
 ( 
 bucket_name 
 ) 
 # Construct a client-side representation of a blob. 
 # Note `Bucket.blob` differs from `Bucket.get_blob` in that it doesn't 
 # retrieve metadata from Google Cloud Storage. As we don't use metadata in 
 # this example, using `Bucket.blob` is preferred here. 
 blob 
 = 
 bucket 
 . 
 blob 
 ( 
 source_blob_name 
 ) 
 blob 
 . 
  download_to_file 
 
 ( 
 file_obj 
 ) 
 print 
 ( 
 f 
 "Downloaded blob 
 { 
 source_blob_name 
 } 
 to file-like object." 
 ) 
 return 
 file_obj 
 # Before reading from file_obj, remember to rewind with file_obj.seek(0). 
 

  # Downloads a blob to a stream or other file-like object. 
 # The ID of your GCS bucket 
 # bucket_name = "your-unique-bucket-name" 
 # Name of a file in the Storage bucket 
 # file_name   = "some_file.txt" 
 # The stream or file (file-like object) to which the contents will be written 
 # local_file_obj = StringIO.new 
 require 
  
 "google/cloud/storage" 
 storage 
  
 = 
  
 Google 
 :: 
 Cloud 
 :: 
  Storage 
 
 . 
  new 
 
 bucket 
  
 = 
  
 storage 
 . 
 bucket 
  
 bucket_name 
 file 
  
 = 
  
 bucket 
 . 
  file 
 
  
 file_name 
 file 
 . 
  download 
 
  
 local_file_obj 
 , 
  
 verify 
 : 
  
 :none 
 # rewind the object before starting to read the downloaded contents 
 local_file_obj 
 . 
 rewind 
 puts 
  
 "The full downloaded file contents are: 
 #{ 
 local_file_obj 
 . 
 read 
 . 
 inspect 
 } 
 "